In recent years, demand for low-priced personal computers (PCs) has increased, and therefore, in order to lower the price of PCs, low-priced, and therefore low-efficiency, components are used for building PCs. For example, most of the low-priced notebook type personal computers (hereafter, which are abbreviated as the notebook PCs) are equipped with a display device, which is a device having a liquid crystal display screen etc., whose response speed is merely 50 fps (frame per second) because a high-priced display device can not be used. When such notebook PC is used to play back a 60 fps HD (High Definition) video content on the Internet, since the display device cannot display images (pictures) at rate of more than 50 fps, the problem is encountered that 10 frames per second are dropped.
One way that the above problem can be overcome is by reducing the frame rate of videos so as to be able to be played back by low-performance display devices (refer to patent documents 1-4). Here, most of video content are stored in an MPEG format, especially an MPEG-2 format. Every 15 frames of video content in the MPEG-2 format constitute a group. This group is called GOP (Group of Pictures). Decoding of the MPEG-2 video is performed in units of the GOP, and therefore it is difficult to reduce the frame rate by removing some frames. Moreover, since low-priced notebook PC contains, in order to lower its price, a CPU (Central Processing Unit) with slow operation speed, for instance, 1.6 GHz, it is also difficult to reduce the frame rate by performing process that requires much processing power.